In April, the social network announced it would begin tapping its enormous vault of personal information on users to show them ads on mobile apps outside of Facebook.

At the time, the ads were available only to a small number of advertisers and mobile apps. Now, they can be purchased by any of Facebook’s 1.5 million advertisers, and can appear on any app.

The ad network is potentially big step for Facebook, because it expands the network’s ability to collect revenue beyond Facebook’s borders. That’s particularly important as more advertisers buy Facebook ads, reducing the available space on its website and mobile app.